Here are some digits I just posted to IRC. I was basically running
commit_tests.py over HTTP in various ways, and then using 'wc -l' on the
access_log to see how many requests were fired off to complete those tests.

Here are the numbers:

serf, v2 enabled: 3601 requests
serf, v2 disabled: 4581 requests

So, the addition of HTTP v2 changes to ra-serf has resulted in a 20%
reduction in the number of requests aimed at the server. Those are almost
certainly all PROPFIND and CHECKOUT requests.

neon, trunk today: 2724 requests

Much fewer requests for ra-neon (which has a subset of the HTTP v2 changes
in it), but this isn't a fair comparison because ra-neon uses full REPORTs
for its update operations, whereas ra-serf uses skelta REPORTs with
subsequent GETs and PROPFINDs. Fortunately, as of 1.5, we can tell the
server not to allow those full REPORTs, which forces ra-neon to behave as
ra-serf does in that manner, and gives us a more fair comparison: